US3764966A - Underwater earphone - Google Patents

Abstract

An underwater earphone having a cylindrical casing sealed at one end by the vibratable diaphragm and at the other end by a flexible rubber diaphragm. The casing, including pole pieces and energizing coils is filled with silicone oil providing damping. This construction equalizes the pressure on either side of the vibratable diaphragm and prevents the ingress of water.

Description

United States Patent [191 Abbagnaro Oct. 9, 1973 UNDERWATER EARPHONE [75] Inventor: Louis A. Abbagnaro, Huntington,

Conn.

[73] Assignee: The United States of America as represented by the Secretary of the Navy, Washington, D.C.

[22] Filed: Mar. 8, 1972 [21] Appl. No.: 232,800

[52] US. Cl. 340/14, 340/5 T, 340/8 LF, 340/8 PC [51] Int. Cl H04r 13/00 [58] Field of Search 340/5 R, 5 T, 8 PC, 340/8 LP, 14

[56] References Cited UNITED STATES PATENTS 3,174,129 3/1965 Laughlin et a1. 340/5 T 3,351,900 11/1967 Yamamoto et a1. 340/14 X Primary ExaminerRichard A. Farley AttorneyR. S. Sciascia et a1.

[57] ABSTRACT An underwater earphone having a cylindrical casing sealed at one end by the vibratable diaphragm and at the other end by a flexible rubber diaphragm. The casing, including pole pieces and energizing coils is filled with silicone oil providing damping. This construction equalizes the pressure on either side of the vibratable diaphragm and prevents the ingress of water.

5 Claims, 1 Drawing Figure UNDERWATER EARPHONE BACKGROUND OF THE INVENTION This invention relates generally to underwater communications and, more particularly, to earphones for use underwater. The need for improved communications in water is a prime concern to both military and commerical factions. The increased use of selfcontained underwater breathing apparatus (SCUBA) has allowed the expansion of a mans underwater exploration range at depths of several hundred feet. Major programs such as the U. S. Navys SEALAB, and the commercial programs for explorations and the development of the oceans vast resources have emerged in recent years. These programs have demonstrated the inadequacy of present diver-to-diver and diver-to-ship communications. Critical among the unsolved problems has been the lack of underwater earphones for satisfactory communications.

Past attempts to alleviate this problem have been directed to sealing the internal structure of the earphone from the ingress of water, and to providing a sealed transducer for bone conduction. The difficulties with the first solution was that the ambient water pressure on the outside of the conventional vibrating diaphragm greatly distorted and reduced the audio output. The second solution provided adequate response but it was found that all sense of directional perception and localization was lost.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide highly intelligible auditory underwater communications.

Another object of the instant invention is to provide an earphone capable of operation at great water depths.

A further object of the invention is to provide an underwater earphone couplable to the ear canal.

A still further object of the present invention is to provide an earphone for use underwater that produces adequate and substantially undistorted response.

Still another object of the instant invention is to provide an earphone for use underwater that allows directional perception to be achieved by the user.

Briefly, these and other objects of the present invention are attained by the use of an earphone having a casing sealed on one side by the conventional vibrating diaphragm, and on the other side by a flexible rubber diaphragm, and being completely filled with a silicone oil. This construction not only provides for the proper damping of the vibrating diaphragm to produce an undistorted response; but because of the incompressibility of the silicon oil and the flexing of the rubber diaphragm places an equalizing pressure on the inside of the vibrating diaphragm at pressure depth. Furthermore, the presence of the silicone oil precludes the ingress of water and protects the metal parts of the electromagnetic circuit.

BRIEF DESCRIPTION OF THE DRAWING A more complete understanding of the invention and many of the attendant advantages thereto will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawing, wherein the figure is an isometric view, partially cut away, of the underwater earphone.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawing, in the figure, there is shown generally an underwater earphone 10 based upon the electromagnetic principle of the moving armature type. In a short cylindrical casing 12, made of, for example, hard rubber, phenolic, or a plastic, is mounted an apertured disc-shaped base plate 14, made of a non-magnetic material such as, for example, brass, aluminum or a plastic. A plurality of fluid passages 16 are formed in the base plate 14 in a bolt circle near the periphery thereof providing fluid communication from the front to the rear of the casing 12.

Secured to the apertured disc 14 is a pair of soft iron pole pieces 18. Affixed between these pole pieces at the rear side (right) of the earphone in any conventional manner, such as by cement or other fastening means, is a permenent magnet 20. Each of the pole pieces on the front side (left) is surrounded by an electromagnetic coil 22. The magnetic circuit comprising the magnet, pole pieces, and coils, is completed by a vibrating diaphragm 24 made of a magnetic material such as Vanadium Permandur. The vibrating diaphragm is spaced from the front ends of the pole pieces by an air-gap, and secured and sealed at its periphery to the case 12, by an apertured cap 26 and an O-ring 28. The coils 22 are series connected and thence connected to the signal source via a cable 30 heremetically sealed by means of a gland-type fitting 32 through the side of the casing 12.

The earphone is sealed at the rear of the case by a flexible rubber diaphragm 34 compression sealed to the case by a ring 36 fastened in any suitable manner as by screws 38. A fill hole 40 is provided in the side of the casing 12 to completely fill the sealed casing with a silicone oil 42 and closed by sealing screw 44.

In operation, the earphone 10 is provided with electrical signals via cable 30 to the series connected electromagnetic coils 22 which induce a varying magnetic field in the magnetic circuit comprising pole pieces 18 and magnet 20, causing the diaphragm 24 to vibrate at an audio frequency. This vibration causes movement of the silicone oil 42, which is pumped back and forth through the apertures 16 in the disc 14 thus creating a proper acoustical damping effect. At depths underwater the ambient pressure is exerted on the outside face of the diaphragm 24 tending to force it inwardly. An equal pressure, however, is transmitted to the inside face of the diaphragm through the rubber diaphragm 34 and the incompressible silicone oil 42 flowing through the apertures 16. As it evident the silicone oil also functions to preclude the ingress of water into the casing where it would otherwise corrode the metal parts and destroy the operation of the earphone.

Obviously, numerous modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically described.

I claim:

1. An earphone for use in an underwater environment comprising:

a cylindrical casing;

an electromagnetic circuit contained in said casing including;

a pair of soft iron pole pieces,

a permanent magnet affixed between the ends of said pole pieces, and

a pair of series-connected coils, each of which surrounds one of said pair of pole pieces;

a vibratable diaphragm completing said circuit thru an air gap and sealingly secured at its periphery to the front end of said casing;

a flexible diaphragm sealedly secured at its periphery to the rear end of said casing; and

an incompressible fluid completely filling said casing, whereby an ambient pressure on the face of said vibratable diaphragm is counteracted by an equal 4. The earphone of claim 3 wherein said imcompressible fluid comprises silicone oil.

5. The earphone of claim 4 wherein said electromagnetic circuit is secured to said casing by an apertured disc whereby flow of said silicone oil is permitted from the front to the rear of said casing.

Claims (5)

1. An earphone for use in an underwater environment comprising: a cylindrical casing; an electromagnetic circuit contained in said casing including; a pair of soft iron pole pieces, a permanent magnet affixed between the ends of said pole pieces, and a pair of series-connected coils, each of which surrounds one of said pair of pole pieces; a vibratable diaphragm completing said circuit thru an air gap and sealingly secured at its periphery to the front end of said casing; a flexible diaphragm sealedly secured at its periphery to the rear end of said casing; and an incompressible fluid completely filling said casing, whereby an ambient pressure on the face of said vibratable diaphragm is counteracted by an equal and opposite pressure from the inside of said casing transmitted through said fluid and by said flexible diaphragm in contact with the environment.

2. The earphone of claim 1 wherein said vibratable diaphragm is composed of Vanadium Permandue.

3. The earphone of claim 2 wherein said flexible diaphragm is composed of rubber.

4. The earphone of claim 3 wherein said imcompressible fluid comprises silicone oil.

5. The earphone of claim 4 wherein said electromagnetic circuit is secured to said casing by an apertured disc whereby flow of said silicone oil is permitted from the front to the rear of said casing.

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